Re: [ietf-smtp] EHLO domain validation requirement in RFC 5321

John R Levine <johnl@taugh.com> Sun, 27 September 2020 19:24 UTC

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Date: 27 Sep 2020 15:24:37 -0400
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From: "John R Levine" <johnl@taugh.com>
To: ietf-smtp@ietf.org
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Subject: Re: [ietf-smtp] EHLO domain validation requirement in RFC 5321
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On Sun, 27 Sep 2020, Ned Freed wrote:
>> And, from the standpoint of those large providers, the fight
>> against spam and other sorts of evil behavior would be ever so
>> much easier if they had only a handful of other providers to
>> work with s.t. anything not coming from one of them was suspect.
>> Of course, the way DMARC was developed and deployed might be
>> believed to reflect exactly that attitude.

Having been around while DMARC was being designed, I don't think that was 
even a little bit the plan.  The goal was to deter phishing of major 
targets like Paypal.  Then AOL and Yahoo abused it and it's been downhill 
from there.

We have a problem that I think is insoluble: there is a long tail of mail 
senders, most of people in the tail don't know what they're doing, and 
spammers have made it impossible to give senders the benefit of the doubt. 
Given the prevalence and maliciousness of spam, much of which comes from 
compromised hosts whose nominal owners have no clue, if it doesn't look 
squeaky clean, it's probably malware.

R's,
John